1. Field of the Invention
The present invention relates to digital audio processing, and, in particular, to the detection and encoding of silent periods during speech coding.
2. Description of the Related Art
It is known in the art to compress digital audio signals for more efficient transmission and/or storage. Speech coding refers to the compression of digital audio signals corresponding to human speech. Speech coding may be applied in a variety of situations. For example, speech coding may be used in audio conferencing between two or more remotely located participants to compress the audio signals from each participant for efficient transmission to the other participants. Speech coding may also be used in other situations to compress audio streams for efficient storage for future playback.
It is also known in the art to distinguish between periods of silence and periods of non-silence during speech coding. Those skilled in the art understand that the term "silence" refers to period in which there is no speech. In fact, the audio environment may have significant levels of background noise. As a result, silent periods typically are not really silent at all. Various schemes have been proposed for determining which sequences of digital audio signals correspond to speech (i.e., non-silent periods) and which sequences correspond to silence (i.e., silent periods).
Traditionally, digital audio processing such as speech coding has been performed on specially designed digital signal processing (DSP) chips. These DSP chips are specifically designed to handle the high processing loads involved in digital audio processing. As general-purpose processors become faster and more powerful, it is becoming possible to shift more and more of such digital audio processing from DSPs to general-purpose processors. What is needed is efficient algorithms for implementing digital audio processing in "software" on general-purpose processors rather than in "hardware" on DSPs.
Further objects and advantages of this invention will become apparent from the detailed description of a preferred embodiment which follows.